    <div class="refentry" id="glGetProgramInterface">
      <div class="titlepage"></div>
      <div class="refnamediv">
        <h2>Name</h2>
        <p>glGetProgramInterface — query a property of an interface in a program</p>
      </div>
      <div class="refsynopsisdiv">
        <h2>C Specification</h2>
        <div class="funcsynopsis">
          <table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
            <tr>
              <td>
                <code class="funcdef">void <strong class="fsfunc">glGetProgramInterfaceiv</strong>(</code>
              </td>
              <td>GLuint <var class="pdparam">program</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLenum <var class="pdparam">programInterface</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLenum <var class="pdparam">pname</var>, </td>
            </tr>
            <tr>
              <td> </td>
              <td>GLint * <var class="pdparam">params</var><code>)</code>;</td>
            </tr>
          </table>
          <div class="funcprototype-spacer"> </div>
        </div>
      </div>
      <div class="refsect1" id="parameters">
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>program</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    The name of a program object whose interface to query.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>programInterface</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    A token identifying the interface within <em class="parameter"><code>program</code></em> to query.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>pname</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    The name of the parameter within <em class="parameter"><code>programInterface</code></em> to query.
                </p>
            </dd>
            <dt>
              <span class="term">
                <em class="parameter">
                  <code>params</code>
                </em>
              </span>
            </dt>
            <dd>
              <p>
                    The address of a variable to retrieve the value of <em class="parameter"><code>pname</code></em> for the program interface.
                </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1" id="description">
        <h2>Description</h2>
        <p>
            <code class="function">glGetProgramInterfaceiv</code> queries the property of the interface identifed
            by <em class="parameter"><code>programInterface</code></em> in <em class="parameter"><code>program</code></em>, the property name of
            which is given by <em class="parameter"><code>pname</code></em>.
        </p>
        <p>
            <em class="parameter"><code>program</code></em> must be the name of an existing program object. <em class="parameter"><code>programInterface</code></em>
            is the name of the interface within <em class="parameter"><code>program</code></em> to query and must be one of the following
            values:
        </p>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term">
                <code class="constant">GL_UNIFORM</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active uniforms within <em class="parameter"><code>program</code></em>.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_UNIFORM_BLOCK</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active uniform blocks within <em class="parameter"><code>program</code></em>.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_ATOMIC_COUNTER_BUFFER</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active atomic counter buffer binding points within <em class="parameter"><code>program</code></em>.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_PROGRAM_INPUT</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active input variables used by the first shader stage of <em class="parameter"><code>program</code></em>.
                        If <em class="parameter"><code>program</code></em> contains multiple shader stages then input variables from any stage other than the first
                        will not be enumerated.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_PROGRAM_OUTPUT</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active output variables produced by the last shader stage of <em class="parameter"><code>program</code></em>.
                        If <em class="parameter"><code>program</code></em> contains multiple shader stages then output variables from any stage other than the last
                        will not be enumerated.
                    </p>
            </dd>
            <dt>
              <span class="term"><code class="constant">GL_VERTEX_SUBROUTINE</code>, </span>
              <span class="term"><code class="constant">GL_TESS_CONTROL_SUBROUTINE</code>, </span>
              <span class="term"><code class="constant">GL_TESS_EVALUATION_SUBROUTINE</code>, </span>
              <span class="term"><code class="constant">GL_GEOMETRY_SUBROUTINE</code>, </span>
              <span class="term"><code class="constant">GL_FRAGMENT_SUBROUTINE</code>, </span>
              <span class="term">
                <code class="constant">GL_COMPUTE_SUBROUTINE</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active subroutines for the vertex, tessellation control, tessellation evaluation,
                        geometry, fragment and compute shader stages of <em class="parameter"><code>program</code></em>, respectively.
                    </p>
            </dd>
            <dt>
              <span class="term"><code class="constant">GL_VERTEX_SUBROUTINE_UNIFORM</code>, </span>
              <span class="term"><code class="constant">GL_TESS_CONTROL_SUBROUTINE_UNIFORM</code>, </span>
              <span class="term"><code class="constant">GL_TESS_EVALUATION_SUBROUTINE_UNIFORM</code>, </span>
              <span class="term"><code class="constant">GL_GEOMETRY_SUBROUTINE_UNIFORM</code>, </span>
              <span class="term"><code class="constant">GL_FRAGMENT_SUBROUTINE_UNIFORM</code>, </span>
              <span class="term">
                <code class="constant">GL_COMPUTE_SUBROUTINE_UNIFORM</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active subroutine uniform variables used by the vertex, tessellation control, tessellation evaluation,
                        geometry, fragment and compute shader stages of <em class="parameter"><code>program</code></em>, respectively.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_TRANSFORM_FEEDBACK_VARYING</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of output variables from the last non-fragment stage of <em class="parameter"><code>program</code></em> that would be
                        captured if transform feedback were active.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_BUFFER_VARIABLE</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active buffer variables used by <em class="parameter"><code>program</code></em>.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_SHADER_STORAGE_BLOCK</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active shader storage blocks used by <em class="parameter"><code>program</code></em>.
                    </p>
            </dd>
            <dt>
              <span class="term">
                <code class="constant">GL_TRANSFORM_FEEDBACK_BUFFER</code>
              </span>
            </dt>
            <dd>
              <p>
                        The query is targeted at the set of active buffer binding points to which output variables in the
                        <code class="constant">GL_TRANSFORM_FEEDBACK_VARYING</code> interface are written.
                    </p>
            </dd>
          </dl>
        </div>
        <p>
            <em class="parameter"><code>pname</code></em> identifies the property of <em class="parameter"><code>programInterface</code></em>
            to return in <em class="parameter"><code>params</code></em>.
        </p>
        <p>
            If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_ACTIVE_RESOURCES</code>, the value returned is the number of
            resources in the active resource list for <em class="parameter"><code>programInterface</code></em>.  If the list
            of active resources for <em class="parameter"><code>programInterface</code></em> is empty, zero is returned.
        </p>
        <p>
            If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_MAX_NAME_LENGTH</code>, the value returned is the length of the
            longest active name string for an active resource in <em class="parameter"><code>programInterface</code></em>.
            This length includes an extra character for the null terminator.  If the
            list of active resources for <em class="parameter"><code>programInterface</code></em> is empty, zero is
            returned.  It is an error to specify <code class="constant">GL_MAX_NAME_LENGTH</code> when <em class="parameter"><code>programInterface</code></em>
            is <code class="constant">GL_ATOMIC_COUNTER_BUFFER</code>, as active atomic counter buffer resources are
            not assigned name strings.
        </p>
        <p>
            If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_MAX_NUM_ACTIVE_VARIABLES</code>, the value returned is the number
            of active variables belonging to the interface block or atomic counter
            buffer resource in <em class="parameter"><code>programInterface</code></em> with the most active variables.  If
            the list of active resources for <em class="parameter"><code>programInterface</code></em> is empty, zero is
            returned.  When <em class="parameter"><code>pname</code></em> is <code class="constant">GL_MAX_NUM_ACTIVE_VARIABLES</code>, <em class="parameter"><code>programInterface</code></em>
            must be <code class="constant">GL_UNIFORM_BLOCK</code>, <code class="constant">GL_ATOMIC_COUNTER_BUFFER</code>, or <code class="constant">GL_SHADER_STORAGE_BLOCK</code>.
        </p>
        <p>
            If <em class="parameter"><code>pname</code></em> is <code class="constant">GL_MAX_NUM_COMPATIBLE_SUBROUTINES</code>, the value returned is the
            number of compatible subroutines belonging to the active subroutine
            uniform in <em class="parameter"><code>programInterface</code></em> with the most compatible subroutines.  If
            the list of active resources for <em class="parameter"><code>programInterface</code></em> is empty, zero is
            returned. When <em class="parameter"><code>pname</code></em> is <code class="constant">GL_MAX_NUM_COMPATIBLE_SUBROUTINES</code>,
            <em class="parameter"><code>programInterface</code></em> must be one of <code class="constant">GL_VERTEX_SUBROUTINE_UNIFORM</code>,
            <code class="constant">GL_TESS_CONTROL_SUBROUTINE_UNIFORM</code>, <code class="constant">GL_TESS_EVALUATION_SUBROUTINE_UNIFORM</code>,
            <code class="constant">GL_GEOMETRY_SUBROUTINE_UNIFORM</code>, <code class="constant">GL_FRAGMENT_SUBROUTINE_UNIFORM</code>, or
            <code class="constant">GL_COMPUTE_SUBROUTINE_UNIFORM</code>.
        </p>
      </div>
      <div class="refsect1" id="errors">
        <h2>Errors</h2>
        <p>
            <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>identifier</code></em>
            is not one of the accepted object types.
        </p>
        <p>
            <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>program</code></em>
            is not the name of an existing sync object.
        </p>
        <p>
            <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>bufSize</code></em> is
            zero.
        </p>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>pname</code></em> is <code class="constant">GL_MAX_NAME_LENGTH</code> and
            <em class="parameter"><code>programInterface</code></em> is <code class="constant">GL_ATOMIC_COUNTER_BUFFER</code> or <code class="constant">GL_TRANSFORM_FEEDBACK_BUFFER</code>,
            since active atomic counter and transform feedback buffer resources are not assigned name strings.
        </p>
        <p>
            <code class="constant">GL_INVALID_OPERATION</code> error is generated if <em class="parameter"><code>pname</code></em> is
            <code class="constant">GL_MAX_NUM_ACTIVE_VARIABLES</code> and <em class="parameter"><code>programInterface</code></em> is not <code class="constant">GL_UNIFORM_BLOCK</code>,
            <code class="constant">GL_SHADER_STORAGE_BLOCK</code>, <code class="constant">GL_ATOMIC_COUNTER_BUFFER</code>, or
            <code class="constant">GL_TRANSFORM_FEEDBACK_BUFFER</code>.
        </p>
        <p>
            If not NULL, <em class="parameter"><code>length</code></em> and <em class="parameter"><code>label</code></em> should be addresses
            to which the client has write access, otherwise undefined behavior, including process termination
            may occur.
        </p>
      </div>
      <div class="refsect1" id="associatedgets">
        <h2>Associated Gets</h2>
        <p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAX_LABEL_LENGTH</code>.
        </p>
      </div>
      {$pipelinestall}{$examples}
      <div class="refsect1" id="versions">
        <h2>Version Support</h2>
        <div class="informaltable">
          <table style="border-collapse: collapse; border-top: 2px solid ; border-bottom: 2px solid ; border-left: 2px solid ; border-right: 2px solid ; ">
            <colgroup>
              <col style="text-align: left; "/>
              <col style="text-align: center; " class="firstvers"/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; "/>
              <col style="text-align: center; " class="lastvers"/>
            </colgroup>
            <thead>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; ">

            </th>
                <th style="text-align: center; border-bottom: 2px solid ; " colspan="12">
                <span class="bold"><strong>OpenGL Version</strong></span>
            </th>
              </tr>
              <tr>
                <th style="text-align: left; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>Function / Feature Name</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>2.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>3.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.0</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.1</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.2</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.3</strong></span>
            </th>
                <th style="text-align: center; border-right: 2px solid ; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.4</strong></span>
            </th>
                <th style="text-align: center; border-bottom: 2px solid ; ">
                <span class="bold"><strong>4.5</strong></span>
            </th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td style="text-align: left; border-right: 2px solid ; ">
                  <code class="function">glGetProgramInterfaceiv</code>
                </td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">-</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; border-right: 2px solid ; ">✔</td>
                <td style="text-align: center; ">✔</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1" id="seealso">
        <h2>See Also</h2>
        <p>
            <a class="citerefentry" href="glPushDebugGroup"><span class="citerefentry"><span class="refentrytitle">glPushDebugGroup</span></span></a>,
            <a class="citerefentry" href="glPopDebugGroup"><span class="citerefentry"><span class="refentrytitle">glPopDebugGroup</span></span></a>,
            <a class="citerefentry" href="glObjectLabel"><span class="citerefentry"><span class="refentrytitle">glObjectLabel</span></span></a>,
            <a class="citerefentry" href="glGetObjectLabel"><span class="citerefentry"><span class="refentrytitle">glGetObjectLabel</span></span></a>.
        </p>
      </div>
      <div class="refsect1" id="Copyright">
        <h2>Copyright</h2>
        <p>
            Copyright © 2013-2014 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <a class="link" href="https://opencontent.org/openpub/" target="_top">https://opencontent.org/openpub/</a>.
        </p>
      </div>
    </div>
